EMC & Thermal Management Catch here
Helping engineers overcome the thermal
challenges of EMC By Tom Gregory, 6SigmaET product manager, Future Facilities A
cross almost every industry, the last decade has seen a signifi cant rise in the number of electronic, electrical and communication systems.
This complexity, combined with the need for devices to be faster, smaller and more digitally connected, has forced engineers to fi nd new and effective ways to ensure that their components remain compatible with one another.
Any interferences to these components can cause a wide range of issues, spanning from a minor audio glitch to a failure of mission critical systems such as aircraft controls, automotive safety systems, or medical devices. Electromagnetic interferences (EMI) is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.
When deciding how best to deal with EMI, it’s key to remember that it is always more effi cient and less expensive to deal with interference early — the further down the design chain you are, the more diffi cult and expensive it can be to mitigate EMI problems.
What to do about EMI
The goal of all electronic designers will be to achieve electromagnetic compatibility (EMC) in their designs — not only to assure proper operation, but to meet the various mandatory EMC requirements imposed by legislation around the world. Without correct certifi cation, most markets will prohibit sales and there are repercussions for using non- compliant products in many industries too. EMC makes sure that electronic devices don’t emit excessive electromagnetic emissions and that equipment continues to function as intended when exposed to certain levels of external interference.
In electronics design, beyond fundamental board layouts, probably the most common way of ensuring that components work correctly when they are in close proximity, is EMC shielding — also known as RF shielding when it’s used to block radio frequency electromagnetic radiation.
Shielding works by enclosing a component in conductive materials, including copper, steel, copper alloy 770 and aluminium. These shielding components have associated thermal implications because you
are limiting airfl ow over components and trapping heat where it’s generated. As such, even more thorough consideration needs to be given to how to transfer heat away from components, without compromising the shielding or adding further sources of electromagnetic interference.
Holes can be added to shielding cans and are often necessary to ensure the component does not overheat. Holes in shielding cans must also be much smaller than the wavelength of the highest frequency for which shielding is required.
Shielding cans made from high conductivity materials can also be used as heat spreaders to spread heat away from high powered components.
Getting the right balance
Both adequate thermal management and EMC shielding are vital to the creation, and reliable functioning, of electronics components. But with EMC shielding having the potential to limit or even negatively impact thermal management across designs, engineers need to seriously consider how they balance these two needs and which they should prioritise. To improve the speed of their design solutions, engineers need to consider their shielding elements and thermal layouts together, as early on in the design process as possible. Rather than producing costly physical prototypes, the use of thermal simulation software provides the best opportunity to run these investigations, trailing different layouts and designs to determine the best balance between heat fl ow and shielding. Using electronics CFD software which is quick and accurate, engineers can test multiple designs, shapes and material thicknesses to fi gure out what works best for their devices.
www.cieonline.co.uk
For example, using simulation it’s possible to test the difference between a solid EMC shield, a shield with vents for heat fl ow, or gridded shield with multiple holes for ventilation. Alternatively, adopting a fan to force-cool part of a design may work thermally and be very cost effective, but could also introduce localised electrical noise and a pathway through which EMI can pass.
Selecting the right thermal simulation tool for EMC shielding When attempting the right thermal and EMC design balance, it’s important to select the appropriate tools.
Thermal simulation software like 6SigmaET generally provides a wide variety of options and materials to model shielding cans. It also provides a variety of models for other thermal solutions including fans, heatsinks and thermal interface material (TIM). Where a tightly enclosed shielding is required, these all provide viable options for board-level thermal management.
Each industry sector comes with unique design challenges. In the case of aerospace and defence, engineers may also need to ensure that their designs still operate at a variety of altitudes. For some industries like automotive, aerospace and healthcare, there are even a stricter requirement to ensure their products function properly in their electromagnetic (EM) environment while still fulfi lling the related and growing number of EMC standards and regulations.
When selecting the right thermal simulation approach, all of these factors should be taken into account because the earlier EMC issues are factored into any design fl ow, the more elegantly integrated they become.
futurefacilities.com Components in Electronics June 2021 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54
